Green sand mold forming sensor and green sand mold formability evaluation method

ABSTRACT

A green sand mold molding sensor that can measure the pressure applied to a parting plane of a green sand mold in order to determine the quality (casting mold strength) of a molded green sand mold. A green sand mold molding sensor including a pressure sensor for evaluating the molding properties of a green sand mold molded by a casting mold molding machine, wherein the pressure sensor is embedded in a plate having a model attached thereto.

TECHNICAL FIELD

The present invention is related to a green sand mold molding sensorthat evaluates the moldability of a green sand mold molded by a castingmold molding machine.

BACKGROUND

One of the qualities demanded of a green sand mold (casting mold) moldedby a casting mold molding device is casting mold strength. Normally, inorder to determine whether a molded green sand mold has sufficientcasting mold strength, work is carried out to measure each molded greensand mold individually using a casting mold strength gauge. A method forconfirming whether a molded green sand mold has sufficient casting moldstrength without having to perform such work is desired. Furthermore, amethod for managing the casting mold quality of each molded green sandmold without stopping a process is desired.

For example, Patent Document 1 discloses a method for detectingabnormalities in blowing in and filling of casting sand in a blow-intype casting mold molding machine, wherein an internal pressure ismeasured by a pressure sensor in order to detect abnormalities inblowing in and filling of casting sand.

Further, Patent Document 2 discloses a molding device monitoring systemwhich discovers defective casting molds by using position sensors formeasuring positions of frame-setting cylinders, filling-frame cylinders,and a leveling frame to monitor the height of a parting plane of acasting mold.

CITATION LIST Patent Literature

Patent Document 1: JP 3415497 B

Patent Document 2: JP 3729197 B

SUMMARY OF INVENTION Technical Problem

However, the method for detecting abnormalities in blowing in andfilling of casting sand of Patent Document 1 is capable of detectingsand filling defects only and it is difficult to confirm the precisecasting mold strength. Further, even if the molding device monitoringsystem of Patent Document 2 monitors the height of the parting plane ofthe casting mold, it is difficult to confirm the precise casting moldstrength from the height of the parting plane.

The present invention was achieved in light of the foregoing and has theobjective of providing a green sand mold molding sensor that can measurepressure applied to a parting plane of a green sand mold in order todetermine the quality (casting mold strength) of a molded green sandmold.

Solution to Problem

In order to solve the problem mentioned above and achieve the objective,the green sand mold molding sensor of the present invention comprises apressure sensor for evaluating the moldability of a green sand moldmolded by a casting mold molding machine, wherein the pressure sensor isembedded in a plate having a model attached thereto.

Further, in one embodiment of the present invention, the plate havingthe model attached thereto is a member that constitutes a part of aboundary of a molding space defined by the plate and a metal flaskduring green sand mold molding by the casting mold molding machine.

Further, in one embodiment of the present invention, apressure-receiving surface of the pressure sensor and a surface of theplate are in a flush state.

Further, in one embodiment of the present invention, the pressure sensoris embedded between the wall of the metal flask and the model in theplate at the time of green sand mold molding.

Further, in one embodiment of the present invention, the plate isconfigured to be rectangular, a plurality of the pressure sensors areprovided, and these pressure sensors are embedded in the four corners ofthe plate.

Further, in one embodiment of the present invention, the plate havingthe model attached thereto is divided into a central part having themodel attached thereto and a peripheral part having the pressure sensorembedded therein, and the central part of the plate having the modelattached thereto is configured so as to be attachable and detachable.

Further, in one embodiment of the present invention, the casting moldmolding machine is a flask molding machine and the plate is placed on acarrier.

Further, in one embodiment of the present invention, the casting moldmolding machine is a flaskless molding machine and the model is attachedto both surfaces of the plate.

Further, in one embodiment of the present invention, the casting moldmolding machine is a flaskless molding machine and the plate is placedon a shuttle dolly.

Further, in one embodiment of the present invention, the pressure sensoris fixed to the plate by a screwing means.

Further, in one embodiment of the present invention, the pressure sensoris a fluid sensor.

Further, in one embodiment of the present invention, the size of thepressure-receiving surface of the pressure sensor is 5-30 mm indiameter.

Further, a method for evaluating green sand mold moldability in thepresent invention evaluates moldability of a green sand mold molded by acasting mold molding machine by using a green sand mold molding sensorprovided with a pressure sensor embedded in a plate having a modelattached thereto.

Effects of Invention

According to the present invention, an effect is exhibited wherein it ispossible to measure the pressure applied to a parting plane of a greensand mold in order to determine the quality (casting mold strength) of amolded green sand mold.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 represents a schematic of a structure of a casting mold moldingdevice using green sand mold molding sensors according to a firstembodiment.

FIG. 2 represents a configuration of a portion of a casting mold moldingdevice, wherein the portion evaluates casting mold quality.

FIG. 3 is a cross-section view representing details of a portion of aplate having green sand mold molding sensors embedded therein.

FIG. 4 is a cross-section view representing details of a portion of aplate having green sand mold molding sensors embedded therein.

FIG. 5 is a block diagram representing one example of a functionalconfiguration of a casting mold quality evaluation device.

FIG. 6 is a block diagram representing another example of a functionalconfiguration of a casting mold quality evaluation device.

FIG. 7 is a schematic view representing a configuration of an experimentcarried out herein.

FIG. 8 is a graph representing one example of results obtained byrecording, in an integrated amplifier-recorder, temporal changes in thepressure of a green sand mold molding sensor in a squeezing step andanalyzing by computer.

FIG. 9 is a graph summarizing a relationship between peak pressure of agreen sand mold molding sensor and casting mold strength.

FIG. 10 shows one example of a screen displayed on a display unit.

FIG. 11 shows one example of a screen displayed on a display unit.

FIG. 12 shows one example of a screen displayed on a display unit.

FIG. 13 shows steps in a method for evaluating casting mold quality(method for molding a green sand mold) using the casting mold moldingdevice according to the first embodiment.

FIG. 14 shows another example of a plate having green sand mold moldingsensors embedded therein.

FIG. 15 shows another example of a plate having green sand mold moldingsensors embedded therein.

FIG. 16 shows a different mode of a plate.

FIG. 17 represents a schematic of a structure of a casting mold moldingdevice using green sand mold molding sensors according to a secondembodiment.

FIG. 18 represents a configuration of a portion of a casting moldmolding device, wherein the portion evaluates casting mold quality.

FIG. 19 shows steps in a method for evaluating casting mold quality(method for molding a green sand mold) using the casting mold moldingdevice according to the second embodiment.

FIG. 20 shows another example of a plate having green sand mold moldingsensors embedded therein.

FIG. 21 shows another example of a plate having green sand mold moldingsensors embedded therein.

FIG. 22 represents a schematic of a plate structure according to thesecond embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, reference is made to the attached drawings to describeembodiments for implementing the green sand mold molding sensor and themethod for evaluating green sand mold moldability according to thepresent invention.

First Embodiment

The first embodiment will be described with reference to the attacheddrawings. FIG. 1 represents a schematic of a structure of a casting moldmolding device using green sand mold molding sensors according to thefirst embodiment and FIG. 2 represents a configuration of a portion ofthe casting mold molding device, wherein the portion evaluates castingmold quality. The casting mold molding device according to the presentembodiment is a flask molding machine in which, after a green sand mold(casting mold) is molded, a casting frame (metal frame), with the greensand mold contained therein, transfers to the next step.

A casting mold molding device 1 comprises a plate 2 having a model 3attached to an upper surface thereof, a carrier 4, a metal frame 5, afilling frame 6, a squeeze head 7, a squeeze board 8, a table 9, greensand mold molding sensors 10A, 10B, 10C, 10D, wiring 11, and a castingmold quality evaluation device 12. Note that FIG. 2 represents the plate2, the model 3, the carrier 4, and the green sand mold molding sensors10A, 10B, 10C, 10D as seen when viewed from the upper side of thecasting mold molding device 1.

The plate 2 has attached to an upper surface thereof an upper mold (orlower mold) model 3 for molding a shape of a casting in a green sandmold and is rectangular. The plate 2 is formed from aluminum, forexample. The carrier 4 is frame shaped and the plate 2 is placed insidethe frame. In addition, green sand for molding a green sand mold isfilled into a casting mold molding space surrounded by the plate 2, themetal frame 5, the filling frame 6, and the squeeze board 8. The plate 2is a member that constitutes a part of a boundary of the molding spacedefined by the metal frame 5 during green sand mold molding by thecasting mold molding device 1.

For the filling of green sand by the casting mold molding device 1, agravity drop method that uses the weight of the green sand or a blowingmethod that uses an airflow is employed. The gravity drop method is amethod for filling green sand into the casting mold molding space bycausing green sand accumulated in a louvered hopper (not shown) disposedat an upper portion of the casting mold molding device 1 to drop due togravity. Further, the blowing method is a method for filling green sandby blowing green sand inside a sand tank (not shown) into the castingmold molding space.

Here, there follows a brief description of a procedure for loading greensand into the casting mold molding space and compressing. First, themetal frame 5 is placed on top of the carrier 4 and then the fillingframe 6 is overlaid on top of the metal frame 5 to define the castingmold molding space. Next, green sand is loaded into the casting moldmolding space and the squeeze board 8 compresses (squeezes) the greensand. Due thereto, the green sand in the casting mold molding space istamped and a green sand mold is molded.

(Green Sand Mold Molding Sensor)

The green sand mold molding sensors 10A, 10B, 10C, 10D measure, duringmolding of a green sand mold, a pressure value (peak pressure) appliedto a parting plane which is a joining section between the plate 2 and anupper mold (or a lower mold) comprising green sand formed inside thecasting mold molding space. The green sand mold molding sensors 10A,10B, 10C, 10D are pressure sensors. In the present embodiment, the greensand mold molding sensors 10A, 10B, 10C, 10D are embedded in the fourcorners of the plate 2. The reason, which is described later, that thegreen sand mold molding sensors 10A, 10B, 10C, 10D are embedded in sucha way is a result of considering the variation in pressure appliedwithin a plate. By embedding the green sand mold molding sensors 10A,10B, 10C, 10D in the four corners of the plate 2, it is possible to seethe strength distribution of the entire casting mold.

In addition, the green sand mold molding sensors 10A, 10B, 10C, 10D havea pressure-receiving surface for measuring pressure that is exposed inthe upper surface of the plate 2 and measures the pressure value (peakpressure) applied to the parting plane with the green sand mold. At thistime, it is desirable for the pressure-receiving surface of the greensand mold molding sensors 10A, 10B, 10C, 10D and the upper surface ofthe plate 2 to be in a flush state with no differences in leveltherebetween. Due thereto, it is possible to measure the precisepressure. In one example, the green sand mold molding sensors 10A, 10B,10C, 10D are fluid pressure sensors. An earth pressure sensor may alsobe used as the green sand mold molding sensors 10A, 10B, 10C, 10D.

Further, regarding the green sand mold molding sensors 10A, 10B, 10C,10D, a small pressure-receiving surface is desirable, considering thesize of the plate 2 in which the sensors are embedded and the size ofthe model 3, and moreover, that, as described later, the casting moldstrength of a green sand mold is measured by a casting mold strengthgauge at a position where the green sand mold molding sensors 10A, 10B,10C, 10D measure a pressure and that a relationship between the pressurevalue (peak pressure) and the casting mold strength is utilized.Meanwhile, since measurement accuracy is also demanded, with respect tothe size of the pressure-receiving surface, a diameter of approximately5-30 mm is desirable.

FIG. 3 and FIG. 4 are lateral cross-section views representing detailsof a portion of the plate 2 that has green sand mold molding sensors10A, 10B, 10C, 10D embedded therein. FIG. 3 represents a case whereinthe green sand mold molding sensors 10A, 10B, 10C, 10D are of a threadedtype. As shown in FIG. 3, a male thread is formed in a of the green sandmold molding sensors 10A, 10B, 10C, 10D, a female thread is formed in bof the plate 2, and the green sand mold molding sensors 10A, 10B, 10C,10D are screwed to the plate 2.

Meanwhile, FIG. 4 represents a case wherein the green sand mold moldingsensors 10A, 10B, 10C, 10D are of a disk shape. As shown in FIG. 4, thegreen sand mold molding sensors 10A, 10B, 10C, 10D, are placed in a holein the plate 2 and a ring-shaped liner 13 surrounds the outer edge ofthe green sand mold molding sensors 10A, 10B, 10C, 10D. In addition,bolts 14 fix the liner 13 and retain the green sand mold molding sensors10A, 10B, 10C, 10D.

Thus, for the green sand mold molding sensors 10A, 10B, 10C, 10D, it ispossible to use an object having a specification of either a threadedtype or a disk shape and that selection may be made with considerationbe given to an embedding space and attachability of the green sand moldmolding sensors.

The wiring 11 connects the casting mold quality evaluation device 12 tothe green sand mold molding sensors 10A, 10B, 10C, 10D. In the presentembodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D andthe casting mold quality evaluation device 12 are connected by wire(wired communication) via the wiring 11 but may also be connectedwirelessly (wireless communication). For example, it is possible toamplify, by means of an amplifier, for example, the pressure value(pressure value data) detected by the green sand mold molding sensors10A, 10B, 10C, 10D and use wireless communication such as a wireless LANor Bluetooth®, etc., to transmit from a transmitter to the casting moldquality evaluation device 12.

(Casting Mold Quality Evaluation Device)

The casting mold quality evaluation device 12 evaluates the quality of agreen sand mold molded by the casting mold molding device 1 from thepressure value (pressure value data) measured by the green sand moldmolding sensors 10A, 10B, 10C, 10D. FIG. 5 is a block diagramrepresenting a functional configuration of the casting mold qualityevaluation device 12 for wired communication data. The casting moldquality evaluation device 12 comprises a receiving unit 15, anamplification unit 16, an input unit 17, a casting mold strengthcalculation unit 18, a casting mold quality determination unit 19, adisplay unit 20, a transmission unit 21, and a recording unit 22.

The receiving unit 15 receives the pressure value (pressure value data)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. Inthe present example, wired data is received from the wiring 11.

The amplification unit 16 amplifies the signal amount of the receivedpressure value (pressure value data). The amplification unit 16 is, forexample, an amplifier.

The input unit 17 inputs: the casting mold strength of a molded greensand mold measured by a casting mold strength gauge; values of a slope“a” and an intercept “b” in an expression y=ax+b described later; and athreshold value of the casting mold strength of a green sand mold to bemolded. Note that inputting is carried out by a worker. The input unit17 is, for example, a keyboard or a touch panel. In the expressiony=ax+b, “y” is the casting mold strength and “x” is the pressure valuemeasured by the green sand mold molding sensors 10A, 10B, 10C, 10D. Theexpression is a relational expression for determining the casting moldstrength “y” from the slope “a” and the intercept “b” which wereinputted and a measured value “x”.

From the slope “a” and the intercept “b”, which were inputted into theinput unit 17, and from the pressure value (peak pressure) measured bythe green sand mold molding sensors 10A, 10B, 10C, 10D, the casting moldstrength calculation unit 18 calculates the casting mold strength foreach pressure value (peak pressure) measured by the green sand moldmolding sensors 10A, 10B, 10C, 10D by using the relational expressionbetween the measured value and the casting mold strength. A method forcalculating the casting mold strength is described in detail later. Thecasting mold strength calculation unit 18 is, for example, a computer ora PLC.

The casting mold quality determination unit 19 determines the quality ofa molded green sand mold from the threshold value of the casting moldstrength inputted into the input unit 17 and the calculated casting moldstrength. A method for determining the casting mold quality is describedin detail later. The casting mold quality determination unit 19 is, forexample, a computer ora PLC.

The display unit 20 displays: the pressure value (peak pressure)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D;values of the slope “a” and the intercept “b” in the relationalexpression y=ax+b between the casting mold strength inputted by a workerusing the input unit 17 and the pressure value (peak pressure); thethreshold value of the casting mold strength of a green sand mold to bemolded that was inputted by a the worker; a casting mold strengthcalculation result; and a casting mold quality determination result,etc. The display unit 20 is, for example, a liquid crystal display, etc.

The transmission unit 21 transmits fault-determination data to aPatlite® 23, etc. Transmission may be either by wired data or wirelessdata. In addition, a worker that has recognized a defect occurrence in agreen sand mold by confirming that the Patlite 23 is flashing, etc., isto make an X mark on the relevant green sand mold and thereby make itpossible to understand at a glance that that green sand mold is adefective product. A green sand mold that has been recognized as being adefective product does not undergo subsequent steps (molten metalpouring) and after skipping these steps is finally shaken out from themold.

The recording unit 22 records pressure value data, casting mold strengthdata associated with pressure values, casting mold strength calculationresults, and casting mold quality determination results, etc.Furthermore, these data are recorded for each model attached to theplate 2. The recording unit 22 is, for example, a recording medium suchas a semiconductor memory or a magnetic disk, etc. In addition, the datarecorded by the recording unit 22 may be extracted by using a USB memoryor an SD card, etc.

As described earlier, the green sand mold molding sensors 10A, 10B, 10C,10D and the casting mold quality evaluation device 12 may be connectedwirelessly (wireless communication). FIG. 6 is a block diagramrepresenting a functional configuration in the case wherein the pressurevalue (pressure value data) measured by the green sand mold moldingsensors 10A, 10B, 10C, 10D is connected wirelessly (wirelesscommunication) to the casting mold quality evaluation device 12. Thepressure value (pressure value data) measured by the green sand moldmolding sensors 10A, 10B, 10C, 10D is amplified by an amplification unit16′ near the green sand mold molding sensors and wirelessly transmittedfrom a pressure value transmission unit 24 to a receiving unit 15′ ofthe casting mold quality evaluation device 12. The casting mold qualityevaluation device 12 for wireless data shown in FIG. 6 comprises areceiving unit 15′, the input unit 17, the casting mold strengthcalculation unit 18, the casting mold quality determination unit 19, thedisplay unit 20, the transmission unit 21, and the recording unit 22.

After the pressure value (pressure value data) measured by the greensand mold molding sensors 10A, 10B, 10C, 10D has been amplified by theamplification unit 16′, the receiving unit 15′ receives wireless datatransmitted from the pressure value transmission unit 24. Note that thefunctions of the input unit 17, the casting mold strength calculationunit 18, the casting mold quality determination unit 19, the displayunit 20, the transmission unit 21, and the recording unit 22 are thesame as the functions of the casting mold quality evaluation device 12for wired data described earlier.

(Relationship Between Pressure Measured by Green Sand Mold MoldingSensors and Casting Mold Strength of Molded Green Sand Mold)

Next, there follows a description of the relationship between thecasting mold strength of a molded green sand mold and the pressure value(peak pressure) that is applied to the parting plane and measured by thegreen sand mold molding sensors. In order to investigate therelationship between the foregoing, an experiment was carried out byusing a molding machine. FIG. 7 is a schematic view representing aconfiguration of the experiment carried out herein. Note that FIG. 7represents: a positional relationship between a plate and a sensor; anintegrated amplifier-recorder 25 that amplifies and records a signalfrom a pressure sensor; and a computer 26 that is connected to theintegrated amplifier-recorder 25 and performs analysis such as graphingsensor measurement values. The experiment was performed as follows.

1. Green sand mold molding sensors were installed (embedded) in a platemade of aluminum. In this experiment, fluid pressure sensors were usedas the green sand mold molding sensors. Installation locations were setat a total of three locations: in the center of the plate and inopposing corners of the plate. Note that for the sake of descriptionshereinafter, in the drawings, S1 and S2 are the two locations on theline between opposing corners of the plate and close to the respectiveapexes, and S3 is the central section of the plate. The reason forinstalling fluid pressure sensors at the three locations S1, S2, and S3is so as to be able to acquire data in a large pressure range from onemolding, since the force acting on the plate during molding of a greensand mold is high in the central section of the plate and low near themetal frame due to frictional resistance between the metal frame and thegreen sand. Further, since a fluid pressure sensor was also disposed inthe central section of the plate, the present experiment was performedwithout attaching a model.

2. The plate having the green sand mold molding sensors installedtherein was attached to a molding machine and a green sand mold wasmolded. In addition, during a squeezing step, the pressure applied tothe parting plane was measured by the green sand mold molding sensors atthe three locations. Temporal changes in the pressure value weremeasured and recorded in the integrated amplifier-recorder 25. Withrespect to squeezing, pressure was applied gradually up to a setpressure and was released when the set pressure was reached.

3. The casting mold strength of a green sand mold at positions where thepressure was measured by the green sand mold molding sensors wasmeasured by a casting mold strength gauge and the relationship betweenthe pressure value and the casting mold strength was investigated. Notethat with respect to the strength gauge that measured the casting moldstrength, an invasive-type casting mold strength gauge that is widelyused in casting mold factories to evaluate moldability of a green sandmold and that measures the casting mold strength by introducing,approximately 10 mm into the casting mold, a needle having a tipdiameter of approximately 3 mm was used.

In addition, the abovementioned 2 and 3 were carried out on a pluralityof green sand molds and the data were collected. Table 1 summarizesthese experimental conditions.

TABLE 1 SQUEEZING PRESSURE (MPa) 0.3~0. 7 GREEN SAND FILLING METHOD FREEFALL CASTING MOLD STRENGTH INVASIVE-TYPE CASTING MEASURING APPARATUSMOLD STRENGTH GAUGE BASE SAND OF GREEN SAND SILICA SAND PROPERTIES OFGREEN SAND COMPACTABILITY (%) 33 ± 3 COMPRESSIVE STRENGTH (N/cm²) 22.1PERMEABILITY 224

Experimental Results

FIG. 8 is a graph representing one example of results obtained byrecording, in the integrated amplifier-recorder 25, temporal changes inthe pressure of a green sand mold molding sensor in the squeezing stepand analyzing by the computer 26. Note that FIG. 8 represents the casein which squeezing pressure was set at 0.4 MPa and measurements werecarried out at the three locations S1, S2, and S3. As shown in FIG. 8,in this molding machine, the peak pressure was reached in the squeezingstep approximately two seconds after squeezing commenced.

Further, upon confirming the relationship between the position of theplate and the peak pressure, it was understood that the pressure at thecentral section (S3) of the plate is the highest and pressure becomeslower at places (S1, S2) away from the central section. Due thereto, itwas possible to confirm that near the metal frame, the pressurepropagated to the plate decreases due to frictional resistance betweenthe green sand and the metal frame, which was mentioned earlier.Further, in one example of these experimental results, the pressure atthe central section (S3) of the plate was almost the same as the setpressure (0.4 MPa).

FIG. 9 is a graph summarizing, upon having repeated the abovementionedexperiment, the relationship between the casting mold strength and thepeak pressure of the green sand mold molding sensors which varies withthe set squeezing pressure and the filling state of the green sand. Fromthis graph, a positive correlation is seen in the relationship betweenthe peak pressure of the green sand mold molding sensors and the castingmold strength and it is understood that it is possible to represent thisrelationship with a straight line. In addition, from the straight line,it is possible to determine the expression y=ax+b. Here, y is thecasting mold strength and x is the peak pressure. From these results, itwas understood that it is possible to evaluate the casting mold strength(casting mold filling properties) from the peak value of the pressure(squeezing pressure on the parting plane of the green sand mold) of thegreen sand mold molding sensors.

The green sand mold molding sensors measure the pressure when the filledgreen sand is tamped and the tamping force (compression force) reachesthe plate surface. The pressure reaching this plate surface variesdepending on the magnitude of the tamping force, the densitydistribution of the filling of the green sand before tamping (highpressure in high density portions, low pressure in low densityportions), the shape of the model (pattern), and the characteristics ofthe green sand (low pressure in high water content sand, high pressurein low water content sand).

With respect to the evaluation of moldability by using the green sandmold molding sensors, from the relationships

-   -   high peak pressure of green sand mold molding sensor=high        filling density of green sand=high casting mold strength, and    -   low peak pressure of green sand mold molding sensor=low filling        density of green sand=low casting mold strength,        when the peak pressure of the green sand mold molding sensor is        low, there is a concern of defects such as molten metal        infiltration, sand drop/sand inclusion, molten metal leakage,        etc. When the peak pressure of the green sand mold molding        sensor is high, sliding resistance between the model and the        casting mold increases and there is a concern of mold removal        defects. As such, keeping the detected peak pressure of the        green sand mold molding sensors at a suitable level leads to a        reduction in defects.

The pressure conveyed to the green sand mold molding sensors embedded inthe plate varies due to the causes mentioned above and therefore theembedding positions of the green sand mold molding sensors must beplaces where it is possible to ascertain these circumstances.Accordingly, if multiple green sand mold molding sensors are installed,it is possible to detect flaws under more conditions. However, due tospace constraints and from an economic perspective, this is notrealistic and it is desirable to be able to detect and evaluate pressureusing a smaller number of sensors.

As mentioned earlier, for the filling of green sand by the casting moldmolding device 1, a gravity drop method or a blowing method that uses anairflow is employed. In the gravity drop method that uses a louveredhopper, etc., mentioned earlier, a bias when the green sand is loadedinto the louvered hopper may become a bias when loading into the castingmold molding space. Further, in the blowing method, a bias may occurwhen loading into the casting mold molding space due to circumstancessuch as the distance from the blowing-in nozzle, sand blockage in thenozzle opening, etc. These biases appear as biases in the pressurepropagated to the plate 2 due to the subsequent tamping of the greensand. It is necessary to dispose the green sand mold molding sensors bytaking into consideration the occurrence of such biases in initialfilling amounts.

In addition, in cases in which a difference in the measurement value ofa disposed green sand mold molding sensor is outside a predeterminedthreshold value range, it can be determined that the bias of the initialfilling is large and it is possible to take measures such as: improvingthe state in which casting mold sand is loaded into the louvered hopper;adjusting blowing-in air pressure or blowing-in time; or improving thestate (blockage, abrasion, etc.) of the blowing-in nozzle. Further, theflowability of the green sand has an influence when the casting moldsand is loaded into the louvered hopper, when loaded from the louveredhopper to the casting mold molding space, or when blown-in by means ofblowing, etc. This flowability of the green sand varies according tosand properties such as the water content of the green sand and it istherefore possible to adjust the sand by using a sand processing devicesuch as a kneading machine that kneads green sand to be supplied to thecasting mold molding device 1.

Further, when green sand is tamped, the green sand is compressed by atamping force and a pressure is detected by the green sand mold moldingsensors embedded in the plate. The force propagated to the plate isgenerally high in the (planar state) central section of the casting moldand lower in a peripheral section due to sliding resistance (orfrictional resistance) between the green sand and the casting frame sidesurface. In the case of a rectangular casting mold, the force is lowestin corner sections near the casting frame.

As such, in order to evaluate the force (pressure) propagated to theplate due to the magnitude of the tamping force, it is preferable todispose green sand mold molding sensors near the casting frame sidesurface, in particular, in the corner sections. If a measurement valueof a green sand mold molding sensor disposed in this position does notreach a predetermined lower limit threshold value, it can be judged thata sufficient casting mold strength has not been reached and measures toincrease the tamping force can be taken. If the measurement value ishigher than an upper limit threshold value, it can be judged that thecasting mold strength is more than sufficient and measures to decreasethe tamping force can be undertaken.

In the present embodiment, considering the step for filling the greensand and the step for tamping the green sand, the green sand moldmolding sensors 10A, 10B, 10C, 10D are embedded in the four corners ofthe plate 2.

Note that the relationship between the peak value of the pressure of thegreen sand mold molding sensors and the casting mold strength is alsothe same when using another type of flask molding machine or a flasklessmolding machine. As such, this relationship can also be applied in acasting mold molding device of a second embodiment which is describedlater.

(Method for Calculating Casting Mold Strength)

Next, there follows a description of a method for calculating thecasting mold strength by using the casting mold strength calculationunit 18. As mentioned above, it has been ascertained that there is acorrelative relationship between the casting mold strength and the peakvalue of the pressure of the green sand mold molding sensors. Thecasting mold strength calculation unit 18 uses this relationship tocalculate the casting mold strength from the casting mold strengthinputted into the input unit 17 and the pressure value (peak pressure)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D.

Specifically, calculation of the casting mold strength by the castingmold strength calculation unit 18 comprises two steps.

Step 1

A predetermined number of green sand molds are molded in advance and apressure value (peak pressure) during squeezing is measured by the greensand mold molding sensors 10A, 10B, 10C, 10D. Furthermore, the castingmold strength at positions in each of the molded green sand molds wherethe pressure was measured by the green sand mold molding sensors 10A,10B, 10C, 10D is measured and inputted into the input unit 17 by aworker. In addition, a worker determines the expression y=ax+b from therelationship between the casting mold strength and the pressure value(peak pressure).

Note that in the present embodiment, on the basis of the experimentalresults mentioned above, the green sand mold molding sensors 10A, 10B,10C, 10D are embedded in the four corners of the plate 2. By measuringthe pressure applied to the parting plane at these four locations anddetermining a relationship with the casting mold strength, it ispossible to determine casting mold quality by using a small number ofgreen sand mold molding sensors while taking into considerationvariation in pressure on the plate upper surface. Further, when making apredetermined number of moldings, by varying the squeezing pressure, itis possible to determine a relationship between the pressure applied tothe parting plane and the casting mold strength over a wider range.

FIG. 10 shows one example of a screen displayed on the display unit 20.In the present example, first, a predetermined green sand mold is moldedand seven pressure values (peak pressures) measured by the green sandmold molding sensors 10A, 10B at that time are displayed on the screen.Note that it is also possible to switch to a screen which displays sevenpressure values (peak pressures) measured by the green sand mold moldingsensors 10C, 10D, and that furthermore, one screen may be configured sothat seven pressure values (peak values) measured by the green sand moldmolding sensors 10A, 10B, 10C, 10D are displayed on the screen.

In addition, the casting mold strength at positions in each of themolded green sand molds where the green sand mold molding sensors 10A,10B, 10C, 10D were disposed is inputted as an input value by a worker.Here, “Peak pressure A” and “Casting mold strength A” shown in FIG. 10are, respectively, the peak pressure value of the green sand moldmolding sensor 10A and the casting mold strength at the position of thegreen sand mold molding sensor 10A. Further, “Peak pressure B” and“Casting mold strength B” in the FIG. 10 are, respectively, the peakpressure value of the green sand mold molding sensor 10B and the castingmold strength at the position of the green sand mold molding sensor 10B;“Peak pressure C” and “Casting mold strength C” displayed on theswitched screen are, respectively, the peak pressure value of the greensand mold molding sensor 10C and the casting mold strength at theposition of the green sand mold molding sensor 10C; and “Peak pressureD” and “Casting mold strength D” displayed on the switched screen are,respectively, the peak pressure value of the green sand mold moldingsensor 10D and the casting mold strength at the position of the greensand mold molding sensor 10D.

The casting mold strength calculation unit 18 plots the casting moldstrength and the peak value of the pressure of the green sand moldmolding sensors on a graph (in the present example, 7×4=28 places). Inaddition, when a worker inputs predetermined values for the slope “a”and the intersect “b” of the expression, a straight line y=ax+b isdisplayed. While confirming the plots, a worker changes numerical valuesof the slope “a” and the intersect “b”, as appropriate, and upondetermining that there is a linear correlation among the plots,determines a final expression y=ax+b. Note that if there are no problemsin terms of casting mold strength with a green sand mold for which thecasting mold strength has been measured by a worker, it is possible formanufacturing to proceed as-is by carrying out subsequent steps (coresetting step, molten metal pouring step, etc.). Note also that in theabove description, a worker inputted the slope “a” and the intersect “b”of the expression, but these may also be determined by using a computeror a PLC and performing a linear regression by a least-squares method,etc.

Step 2

After determining the expression y=ax+b, molding of the green sand moldcommences. After commencing, the expression y=ax+b is used toautomatically calculate the casting mold strength at the positions ofthe green sand mold molding sensors 10A, 10B, 10C, 10D from the pressurevalue (peak pressure) measured by the green sand mold molding sensors10A, 10B, 10C, 10D. Due thereto, there is no need for a worker tomeasure the casting mold strength separately.

Note that in the present example, the casting mold strength is measuredusing a casting mold strength gauge and the number of peak pressures andcasting mold strengths displayed on the screen is seven each for A andB. However, this may be changed, as appropriate, according to thespecifications of the casting mold molding device 1, specifications suchas shape and size of the green sand mold to be molded, etc., or thespecifications of the green sand.

(Method for Determining Casting Mold Quality)

Next, there follows a description of a method for determining castingmold quality by using the casting mold quality determination unit 19.The casting mold quality determination unit 19 determines the quality ofa green sand mold from the threshold value of the casting mold strengthinputted into the input unit 17 and the casting mold strength calculatedby the casting mold strength calculation unit 18.

Specifically, determination of the casting mold quality by the castingmold quality determination unit 19 comprises two steps.

Step 1

First, a worker inputs a threshold value of the casting mold strength ofa green sand mold to be molded. FIG. 11 shows one example of a screendisplayed on the display unit 20. In the present example, specificthreshold values inputted by a worker are displayed. Here, “Sensor Astrength normal range” in FIG. 11 indicates the lower limit value andthe upper limit value of the casting mold strength at the position ofthe green sand mold molding sensor 10A; “Sensor B strength normal range”in FIG. 11 indicates the lower limit value and the upper limit value ofthe casting mold strength at the position of the green sand mold moldingsensor 10B; “Sensor C strength normal range” in FIG. 11 indicates thelower limit value and the upper limit value of the casting mold strengthat the position of the green sand mold molding sensor 10C; and “Sensor Dstrength normal range” in FIG. 11 indicates the lower limit value andthe upper limit value of the casting mold strength at the position ofthe green sand mold molding sensor 10D. Further, “Casting mold strengthdifference (Max.−Min.) abnormality value” shown in FIG. 11 indicates athreshold value wherein the difference between the maximum and minimumvalues of the casting mold strength determined from the pressure valueof the green sand mold molding sensors 10A, 10B, 10C, 10D is set as anabnormality value.

In the present example, the lower limit value of the casting moldstrength at the position of the green sand mold molding sensors 10A,10B, 10C, 10D is set as 10.0 (N/cm2), the upper limit value of the sameis set as 20.0 (N/cm2), and the threshold value wherein the differencebetween the maximum value and the minimum value of the casting moldstrength at the position of the green sand mold molding sensors 10A,10B, 10C, 10D is set as an abnormality value is set as 5.0 (N/cm2).

Step 2

After the expression y=ax+b is determined by the casting mold strengthcalculation unit 18 and the threshold value of the casting mold strengthis inputted, molding of the green sand mold commences. After commencing,the casting mold strength at the position of the green sand mold moldingsensors 10A, 10B, 10C, 10D is automatically calculated from the pressurevalue (peak pressure) measured by the green sand mold molding sensors10A, 10B, 10C, 10D. In addition, the quality of a green sand mold isdetermined from the inputted threshold value of the casting moldstrength and the calculated casting mold strength. Here, determinationof the quality of a green sand mold is performed as follows. In thepresent example, the threshold values of the casting mold strength A,the casting mold strength B, the casting mold strength C, and thecasting mold strength D are each set as 10.0 (N/cm2) or more and 20.0(N/cm2) or less, and the abnormality threshold value of the differencebetween the maximum value and the minimum value of the casting moldstrength at the positions of the green sand mold molding sensors 10A,10B, 10C, 10D is set as 5.0 (N/cm2) or more.

Accordingly, in the case in which the casting mold strength at theposition of the green sand mold molding sensor 10A is 13.0 (N/cm2), thecasting mold strength at the position of the green sand mold moldingsensor 10B is 12.0 (N/cm2), the casting mold strength at the position ofthe green sand mold molding sensor 10C is 16.0 (N/cm2), and the castingmold strength at the position of the green sand mold molding sensor 10Dis 14.0 (N/cm2), the casting mold strength A, the casting mold strengthB, the casting mold strength C, and the casting mold strength D are allwithin the threshold values. Furthermore, the maximum value of thecasting mold strengths A, B, C, D is 16.0 (N/cm2), the minimum value is12.0 (N/cm2), and the difference between the maximum and the minimum is4.0 (N/cm2), which is within the range, and therefore the casting moldquality determination unit 19 determines that the casting mold qualityis OK.

In contrast thereto, in the case in which the casting mold strength atthe position of the green sand mold molding sensor 10A is 11.0 (N/cm2),the casting mold strength at the position of the green sand mold moldingsensor 10B is 17.0 (N/cm2), the casting mold strength at the position ofthe green sand mold molding sensor 10C is 12.0 (N/cm2), and the castingmold strength at the position of the green sand mold molding sensor 10Dis 16.0 (N/cm2), the casting mold strength A, the casting mold strengthB, the casting mold strength C, and the casting mold strength D are allwithin the threshold values. However, the maximum value of the castingmold strengths A, B, C, D is 17.0 (N/cm2), the minimum value is 11.0(N/cm2), and the difference between the maximum and the minimum is 6.0(N/cm2), which is not within the range, and therefore the casting moldquality determination unit 19 determines that the casting mold qualityis faulty.

FIG. 12 shows one example of a screen displayed on the display unit 20.Here, “Peak pressure A”, “Peak pressure B”, “Peak pressure C”, and “Peakpressure D” in FIG. 12 indicate, respectively, the peak pressure valueof the green sand mold molding sensor 10A, the peak pressure value ofthe green sand mold molding sensor 10B, the peak pressure value of thegreen sand mold molding sensor 10C, and the peak pressure value of thegreen sand mold molding sensor 10D. Further, “Casting mold strength A”,“Casting mold strength B”, “Casting mold strength C”, and “Casting moldstrength D” indicate, respectively, the casting mold strength at theposition of the green sand mold molding sensor 10A calculated by thecasting mold strength calculation unit 18, the casting mold strength atthe position of the green sand mold molding sensor 10B calculated by thecasting mold strength calculation unit 18, the casting mold strength atthe position of the green sand mold molding sensor 10C calculated by thecasting mold strength calculation unit 18, and the casting mold strengthat the position of the green sand mold molding sensor 10D calculated bythe casting mold strength calculation unit 18.

Furthermore, “Casting mold strength difference (Max.−Min.)” in FIG. 12indicates the difference between the maximum value and the minimum valueof the casting mold strengths A, B, C, D. Further, “Determination” inFIG. 12 indicates a determination result for the casting mold quality bythe casting mold quality determination unit 19.

Note that on the screen of the display unit 20 in FIG. 12, a poornumerical value is displayed by shading or coloring the inside of acell, and OK (normal) and FT (faulty) can be understood at a glance.

Note that the threshold values and the difference between the maximumvalue and the minimum value set for the casting mold strength A, thecasting mold strength B, the casting mold strength C, and the castingmold strength D are determined, as appropriate, in accordance with thespecifications of the casting mold molding device 1, specifications suchas shape, size, etc., of the green sand mold to be molded, the site ofthe green sand mold, or the specifications of the green sand, etc. Inaddition, these values are associated with a model number.

In the casting mold molding device 1 of the present embodiment, even ifthe specifications such as shape, size, etc., of a green sand mold to bemolded change, in each case, it is possible for the casting moldstrength calculation unit 18 to calculate the casting mold strength andfor the casting mold quality determination unit 19 to determine thequality of the molded green sand mold from the calculated casting moldstrength.

(Method for Evaluating Casting Mold Quality Using Casting Mold MoldingDevice)

Next, there follows a description of a method for evaluating castingmold quality (method for molding a green sand mold) using the castingmold molding device 1. FIG. 13 shows steps in a method for evaluatingcasting mold quality (method for molding a green sand mold) using thecasting mold molding device 1 according to the first embodiment. Notethat in FIG. 13, a louvered hopper 27 is coupled to the squeeze head 7of the casting mold molding device 1 shown in FIG. 1. The louveredhopper 27 has a structure wherein a predetermined amount of green sandis loaded therein from a green sand transportation device (not shown)and, after having been briefly retained, louvers 28 at a lower portionof the louvered hopper 27 open and the green sand is loaded into thecasting mold molding space.

Molding of a green sand mold by the casting mold molding device 1follows the procedure described below.

1. When molding is commenced, a table 9 rises and thereby a state shownin FIG. 13(a) is achieved. At this time, a predetermined amount of greensand is loaded into the louvered hopper 27 from the green sandtransportation device (not shown).

2. Then, as shown in FIG. 13(b), the louvers 28 at a lower portion ofthe louvered hopper 27 open and the green sand inside the louveredhopper 27 is loaded into the casting mold molding space defined by theplate 2, the metal frame 5 and the filling frame 6.

3. Then, as shown in FIG. 13(c), the coupled squeeze head 7 and louveredhopper 27 move, the squeeze board 8 is arranged directly above thecasting mold molding space, and next, the table 9 rises and thereby thegreen sand inside the casting mold molding space is squeezed(compressed). At this time, the green sand mold molding sensors 10A,10B, 10C, 10D measure the pressure value (peak pressure) at the partingplane. Note that the casting mold is molded in the present step. At thistime, the green sand mold molding sensors 10A, 10B, 10C, 10D are betweenthe wall of the metal frame 5 and the model 3 in the plate 2.

4. The pressure value (peak pressure) at the parting plane istransmitted to the casting mold quality evaluation device 12 and thequality of the green sand mold that has just been molded is evaluated.

Quality evaluation by the casting mold quality evaluation device 12 isperformed after the expression y=ax+b, which represents the relationshipbetween casting mold strength and the peak value of the pressure of thegreen sand mold molding sensors, has been determined in advance. Inaddition, a green sand mold determined to be OK by the casting moldquality evaluation device 12 flows, as-is, along the line and subsequentsteps (molten metal pouring, etc.) are carried out. Meanwhile, a greensand mold determined to be faulty by the casting mold quality evaluationdevice 12 flows, as-is, along the line, but subsequent steps (moltenmetal pouring, etc.) are not carried out. The green sand mold skipsthese steps and, as a casting mold to be discarded, is shaken out fromthe mold in the same way as a green sand mold having a casting moldquality evaluation determined as being OK. Thus, it is possible to makea determination of “good” or “poor” with respect to the quality of amolded casting mold for each frame, which can therefore lead to acasting mold quality assurance for each frame. Further, it is possibleto judge a defect at the time of molding a green sand mold and thereforeit is possible to reduce defects in castings produced. Furthermore, itis possible to omit unnecessary work and therefore it is possible toreduce production costs.

5. Then, in the casting mold molding device 1, the table 9 lowers, thefilling frame 6 separates from the metal frame 5 upper surface, and whenthe table lowers further, the metal frame 5 containing the green sandmold is placed on a roller conveyor connected to subsequent steps suchas core-setting, molten metal pouring, etc., the model 3 is removed fromthe green sand mold, and the lowering of the table 9 stops. Next, themetal frame 5 containing the green sand mold is conveyed on the rollerconveyor to a subsequent step and the metal frame 5 is loaded into thecasting mold molding device 1 in preparation for the next molding. Notethat when the lowering of the table 9 commences, a predetermined amountof green sand is supplied to the louvered hopper 27 with the louvers 28closed.

6. When the metal frame 5 has been loaded in preparation for the nextmolding and the supplying of green sand to the louvered hopper 27 hasbeen completed, the coupled squeeze head 7 and louvered hopper 27 move,the table 9 rises in a state in which the louvered hopper 27 is arrangeddirectly above the casting mold molding space, and molding of the nextgreen sand mold commences.

In addition, pressure value data, casting mold strength data associatedwith pressure values, casting mold strength calculation results, andcasting mold quality determination results, etc., which are producedduring the molding step, are all recorded in the recording unit 22 ofthe casting mold quality evaluation device 12. Therefore, it is possibleto use these numerical values to monitor the operational state of thecasting mold molding device 1 and these numerical values are useful inquality control, maintenance, and troubleshooting of the casting moldmolding device 1. Furthermore, using these numerical values can lead toearly detection of defect causes such as: sand spillage, burn-in of acasting, and mold drop which occur due to filling defects; and swellingof a green sand mold due to molten metal pressure after pouring.

Furthermore, the data recorded in the recording unit 22 are recorded foreach model attached to the plate 2. Therefore, it is possible to compareand examine a state, such as a defect in a green sand mold, withpressure value data, and setting of a more accurate threshold valuebecomes possible.

Further, in the present embodiment, a worker determines the expressiony=ax+b by considering the slope “a” and the intercept “b” of theexpression from the casting mold strengths and peak values of thepressure of the green sand mold molding sensors plotted on a graph.However, it is also possible to configure so that the casting moldstrength calculation unit 18 automatically calculates the expressiony=ax+b from the relationship between the casting mold strength and thepeak value of the pressure of the green sand mold molding sensors byusing a computer or a PLC and performing a linear regression by aleast-squares method, etc.

Further, in the present embodiment, in the case that a molded green sandmold is determined to be a defect, a worker clarifies that the greensand mold in question is a defect. However, it is also possible toconfigure so that a determination result is automatically communicatedto casting mold equipment of a subsequent step (molten metal pouring,etc.). In that case, at a subsequent step, the casting mold equipmentautomatically recognizes that the green sand mold in question is adefect, omits (skips) the step, and finally the green sand mold inquestion is shaken out from the mold.

Further, in the present embodiment, the green sand mold molding sensors10A, 10B, 10C, 10D are embedded in the four corners of the plate 2.However, even if the number of green sand mold molding sensors embeddedin the plate 2 is smaller, it is possible to calculate the relationshipbetween the casting mold strength and the peak value of the pressure ofthe green sand mold molding sensors. In that case, accuracy is slightlylower in comparison with the case in which green sand mold moldingsensors are embedded in four locations, but it is possible to curbcosts.

In that case, it is also possible to embed green sand mold moldingsensors at two locations on a line between opposing corners shown inFIG. 2: positions 10A and 10B; or 10C and 10D. FIGS. 14 and 15 showother examples of the plate 2 having green sand mold molding sensors10A, 10B embedded therein. In FIG. 14, the two green sand mold moldingsensors 10A, 10B are embedded near the central section of the long sidesof the plate 2. In FIG. 15, the two green sand mold molding sensors 10A,10B are embedded near the central section of the short sides of theplate 2.

(Mode of Plate)

FIG. 16 shows a different mode of the plate 2. FIG. 16(a) shows a plate2 a and a plate 2 b which are placed on the carrier 4. In other words,the plate 2 is divided into a central plate 2 a and a peripheral plate 2b. The central plate 2 a and the peripheral plate 2 b are fixed by bolts(not shown).

The model 3 is attached to an upper surface of the central plate 2 a.Further, the green sand mold molding sensors 10A, 10B, 10C, 10D areembedded in the peripheral plate 2 b. The shapes of the central plate 2a and the peripheral plate 2 b are configured while taking intoconsideration the shape of the model for molding in the casting moldmolding device 1 and the positions of the green sand mold moldingsensors mentioned above. The shapes of alignment sections of the centralplate 2 a and the peripheral plate 2 b are configured so as to share acommon shape, and when a model for molding in the casting mold moldingdevice 1 is to be changed, the central plate 2 a which has the model 3attached thereto only needs to be replaced.

FIG. 16(b) shows a state wherein the central plate 2 a is detached. Byloosening the bolts (not shown) and removing only the central plate 2 a,which has the model 3 attached thereto, and attaching a central platehaving a different model attached thereto, it is possible to easilyexchange models without affecting the green sand mold molding sensors.

Thus, according to the green sand mold molding sensor of the firstembodiment, in order to determine the quality of a molded casting(casting mold strength), it is possible to measure, during molding of agreen sand mold, a pressure value (peak pressure) applied to a partingplane which is a joining section between the plate 2 and the upper mold(or lower mold) comprising green sand mold sand formed inside thecasting mold molding space.

Second Embodiment

Next, there follows a description of a second embodiment of the greensand mold molding sensor and the method for evaluating green sand moldmoldability according to the present invention. Note that in the secondembodiment described below, for configurations common with the firstembodiment, the same reference signs are used in the drawings anddescriptions thereof are omitted. In the second embodiment, a flasklessmolding machine, rather than a flask molding machine, is used.

The second embodiment will be described with reference to the attacheddrawings. FIG. 17 represents a schematic of a structure of the castingmold molding device using green sand mold molding sensors according tothe second embodiment and FIG. 18 represents a configuration of aportion of the casting mold molding device, wherein the portionevaluates casting mold quality. The casting mold molding deviceaccording to the present embodiment is a flaskless molding machine inwhich, after a green sand mold is molded, the green sand mold is removedfrom a casting frame.

A casting mold molding device 29 comprises the plate 2 having the model3 attached to the upper and lower surfaces thereof, a shuttle dolly 30,a cope (metal frame) 31, a drag (metal frame) 32, an upper squeeze board33, a lower squeeze board 34, the green sand mold molding sensors 10A,10B, 10C, 10D embedded in the upper surface of the plate 2, green sandmold molding sensors 10E, 10F, 10G, 10H embedded in the lower surface ofthe plate 2, the wiring 11, and the casting mold quality evaluationdevice 12. Note that FIG. 18 represents the plate 2, the model 3attached to the upper surface thereof, the shuttle dolly 30, and thegreen sand mold molding sensors 10A, 10B, 10C, 10D as seen when viewedfrom the upper side of the plate 2 of the casting mold molding device29. Note also that the green sand mold molding sensors 10E, 10F, 10G,10H are embedded in the lower surface of the plate 2 and are thereforenot shown in FIG. 18.

The plate 2 has attached to the upper and lower surfaces thereof a model3 for molding a shape of a casting in a green sand mold and isrectangular. The shuttle dolly 30 has the plate 2 placed thereon andmakes round trips between the inside and the outside of the casting moldmolding device 29 in accordance with the step. The cope 31 has greensand filled therein in order to mold an upper mold of the green sandmold. In other words, the casting mold molding space surrounded by thecope 31, the upper squeeze board 33, and the plate 2 is filled withgreen sand. The drag 32 has green sand filled therein in order to mold alower mold of the green sand mold. In other words, the casting moldmolding space surrounded by the drag 32, the lower squeeze board 34, andthe plate 2 is filled with green sand. The plate 2 is a member thatconstitutes a part of a boundary of the molding space defined by thecope 31 or the drag 32 during green sand mold molding by the castingmold molding device 29.

For the filling of green sand by the casting mold molding device 29, ablowing method that uses an airflow is employed. The blowing method is amethod for filling green sand by blowing in green sand to the upper andlower surfaces of the plate 2 from green sand blowing-in ports 35, 35 ofthe cope 31 and drag 32.

The upper squeeze board 33 and the lower squeeze board 34 act via acylinder (not shown), and the upper and lower green sand molds aremolded simultaneously by tamping and compressing the green sand filledin the cope 31 and the green sand filled in the drag 32.

(Green Sand Mold Molding Sensor)

The green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F,10G, 10H measure, during molding of a green sand mold, a pressure value(peak pressure) applied to a parting plane which is a joining section ofthe plate 2 between the upper mold comprising green sand formed insidethe cope 31 and the lower mold comprising green sand formed inside thedrag 32. The green sand mold molding sensors 10A, 10B, 10C, 10D and 10E,10F, 10G, 10H are pressure sensors. In the present embodiment, the greensand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H areembedded in the four corners of the upper and lower surfaces of theplate 2. The reason that the green sand mold molding sensors 10A, 10B,10C, 10D, and 10E, 10F, 10G, 10H are embedded in such a way is the sameas the reason described in the first embodiment.

In addition, the green sand mold molding sensors 10A, 10B, 10C, 10D, and10E, 10F, 10G, 10H have a pressure-receiving surface for measuringpressure that is exposed in the upper surface or lower surface of theplate 2 and measures the pressure value (peak pressure) applied to theparting plane above and below the plate 2. At this time, it is desirablefor the pressure-receiving surface of the green sand mold moldingsensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H and the upper andlower surfaces of the plate 2 to be in a flush state with no differencesin level therebetween. Due thereto, it is possible to measure theprecise pressure.

The wiring 11 connects the casting mold quality evaluation device 12 tothe green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F,10G, 10H. In the present embodiment, the green sand mold molding sensors10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H, and the casting mold qualityevaluation device 12 are connected by wire via the wiring 11 but mayalso be connected wirelessly. For example, it is possible to usewireless communication such as a wireless LAN or Bluetooth, etc., totransmit the pressure value (pressure value data) detected by the greensand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H tothe casting mold quality evaluation device 12.

The casting mold quality evaluation device 12 evaluates the quality ofthe green sand mold molded by the casting mold molding device 29 fromthe pressure value (pressure value data) measured by the green sand moldmolding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H. The castingmold quality evaluation device 12 comprises a receiving unit 15, anamplification unit 16, an input unit 17, a casting mold strengthcalculation unit 18, a casting mold quality determination unit 19, adisplay unit 20, a transmission unit 21, and a recording unit 22.

The receiving unit 15 receives the pressure value (pressure value data)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D and10E, 10F, 10G, 10H. The amplification unit 16 amplifies the signalamount of the received pressure value (pressure value data). The inputunit 17 inputs: the casting mold strength of a molded green sand mold,measured by a casting mold strength gauge; values of a slope “a” and anintercept “b” of the expression y=ax+b; and a threshold value of thecasting mold strength of a green sand mold to be molded, etc.

From the casting mold strength inputted into the input unit 17 and thepressure value (peak pressure) measured by the green sand mold moldingsensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H, the casting moldstrength calculation unit 18 uses the relational expression between thecasting mold strength and the measurement values to calculate thecasting molding strength for each pressure value (peak pressure)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D and10E, 10F, 10G, 10H.

The casting mold quality determination unit 19 determines the quality ofa molded green sand mold from the threshold value of the casting moldstrength inputted into the input unit 17 and the calculated casting moldstrength. The display unit 20 displays on a screen: the pressure value(peak pressure) measured by the green sand mold molding sensors 10A,10B, 10C, 10D and 10E, 10F, 10G, 10H; values of the slope “a” and theintercept “b” of the relational expression y=ax+b between the castingmold strength inputted by a worker using the input unit 17 and thepressure value (peak pressure); the threshold value of the casting moldstrength of a green sand mold to be molded that was inputted by aworker; the casting mold strength calculation result; and the castingmold quality determination result, etc.

The transmission unit 21 transmits fault-determination data to thePatlite 23, etc. The recording unit 22 records pressure value data,casting mold strength data associated with pressure values, casting moldstrength calculation results, and casting mold quality determinationresults, etc.

(Method for Evaluating Casting Mold Quality Using Casting Mold MoldingDevice)

Next, there follows a description of a method for evaluating castingmold quality (method for molding a green sand mold) using the castingmold molding device 29. FIG. 19 shows steps in a method for evaluatingcasting mold quality (method for molding a green sand mold) using thecasting mold molding device 29 according to the second embodiment. Notethat in FIG. 19, a sand tank 36 is adjacent to the casting mold moldingdevice 29 shown in FIG. 17. A predetermined amount of green sand isloaded into the sand tank 36 from the green sand transportation device(not shown) and, after having been briefly retained, a loading hole isclosed and when compressed air is supplied inside the sand tank 36,green sand is filled by being blown into the upper and lower castingmold molding spaces via green sand blowing-in ports 35, 35 in the cope31 and the drag 32.

Molding of a green sand mold by the casting mold molding device 29follows the procedure described below.

1. When molding commences, from the state shown in FIG. 19(a), theshuttle dolly 30 having placed thereon the plate 2, which has the models3, 3 attached thereto and the green sand mold molding sensors 10A, 10B,10C, 10D and 10E, 10F, 10G, 10H embedded therein, moves between the cope31 and the drag 32.

2. Next, the lower squeeze board 34 and the drag 32 rise, lift the plate2 from the shuttle dolly 30, and when the state shown in FIG. 19(b) isset, compressed air is supplied to the sand tank 36 and green sand isfilled by being blown into the upper and lower casting mold moldingspaces via the green sand blowing-in ports 35, 35 in the cope 31 and thedrag 32.

3. Next, due to the action of a cylinder (not shown), the upper andlower squeeze boards 33, 34 squeeze (compress) the green sand inside thecope 31 and the drag 32 and the state shown in FIG. 19(c) is achieved.At this time, the green sand mold molding sensors 10A, 10B, 10C, 10D and10E, 10F, 10G, 10H measure the pressure value (peak pressure) at theparting plane. Note that green sand molds are molded in the presentstep. At this time, the green sand mold molding sensors 10A, 10B, 10C,10D and 10E, 10F, 10G, 10H are between the model 3 and the walls of thecope 31 and the drag 32 of the plate 2. At this time, the measuredpressure value (peak pressure) is transmitted to the casting moldquality evaluation device 12 and the quality of the green sand mold thathas just been molded is evaluated.

Quality evaluation by the casting mold quality evaluation device 12 isperformed after the expression y=ax+b, which represents the relationshipbetween casting mold strength and the peak value of the pressure of thegreen sand mold molding sensors, has been determined in advance. Inaddition, a green sand mold determined to be OK by the casting moldquality evaluation device 12 flows, as-is, along the line and subsequentsteps (molten metal pouring, etc.) are carried out. Meanwhile, a greensand mold determined to be faulty by the casting mold quality evaluationdevice 12 flows, as-is, along the line, but subsequent steps (moltenmetal pouring, etc.) are not carried out. The green sand mold skipsthese steps and, as a casting mold to be discarded, is shaken out fromthe mold in the same way as a green sand mold for which the casting moldquality is determined to be OK.

4. Next, the lower squeeze board 34 and the drag 32 lower and when theplate 2 is placed on the shuttle dolly 30, a state in which the models3, 3, are removed from the upper and lower green sand molds is reached.Then, the shuttle dolly 30 moves to the position shown in FIG. 19(a) andwhen the lower squeeze board 34 and the drag 32 rise again, moldalignment of the upper and lower green sand molds is carried out byaligning the cope 31 and the drag 32. At this time, the upper and lowergreen sand molds are in a state of being sandwiched by the upper squeezeboard 33 and the lower squeeze board 34. From this state, when the uppersqueeze board 33 and the lower squeeze board 34 lower, the aligned upperand lower green sand molds are lowered and removed from the cope 31 andthe drag 32 to reach the state shown in FIG. 19(d).

5. The aligned upper and lower green sand molds are transported from thecasting mold molding device 29 to a line of the next step.

In addition, pressure value data, casting mold strength data associatedwith pressure values, casting mold strength calculation results, andcasting mold quality determination results, etc., which are producedduring the molding step, are all recorded in the recording unit 22 ofthe casting mold quality evaluation device 12. Therefore, it is possibleto use these numerical values to monitor the operational state of thecasting mold molding device 29 and these numerical values are useful inquality control, maintenance, and troubleshooting of the casting moldmolding device 29. Furthermore, using these numerical values can lead toearly detection of defect causes such as: sand spillage, burn-in of acasting, and mold drop which occur due to filling defects; and swellingof a green sand mold due to molten metal pressure after pouring.

Further, in the present embodiment, the green sand mold molding sensors10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H are embedded in the fourcorners of the upper and lower surfaces of the plate 2 near the cope 31and the drag 32. However, even if the number of green sand mold moldingsensors embedded in the plate 2 is small, it is possible to calculatethe relationship between the casting mold strength and the peak value ofthe pressure of the green sand mold molding sensors. In that case,accuracy is slightly lower in comparison with the case in which greensand mold molding sensors are embedded in four locations, but it ispossible to curb costs.

In that case, it is also possible to set two locations 10A, 10B or 10C,10D on a line between opposing corners of the upper surface of the plate2 shown in FIG. 18 or to set two locations 10E, 10F or 10G, 10H on aline between opposing corners of the lower surface of the plate 2. FIGS.20 and 21 show other examples wherein the plate 2 upper surface hasgreen sand mold molding sensors 10A, 10B embedded therein. In FIG. 20,the two green sand mold molding sensors 10A, 10B are embedded near thecentral section of the long sides of the plate 2. In FIG. 21, the twogreen sand mold molding sensors 10A, 10B are embedded near the centralsection of the short sides of the plate 2. It is possible to dispose themolding sensors 10E, 10F in the same state in the lower surface of theplate 2. Due to the arrangement of these molding sensors, it is possibleto ascertain a bias in the filling amount, etc., between right and leftof the green sand blowing-in ports 35, 35, or in the proximity ordistance of the green sand blowing-in ports 35, 35.

(Mode of Plate)

FIG. 22 shows a different mode of the plate 2 wherein the model 3 isattached to the upper and lower surfaces thereof. FIG. 22(a) shows aplate 2 a and a plate 2 b which are placed on the shuttle dolly 30. Inother words, the plate 2 is divided into a central plate 2 a and aperipheral plate 2 b. The central plate 2 a and the peripheral plate 2 bare fixed by bolts (not shown).

The model 3 is attached to upper and lower surfaces of the central plate2 a. Further, the green sand mold molding sensors 10A, 10B, 10C, 10D areembedded in the upper surface of the peripheral plate 2 b and the greensand mold molding sensors 10E, 10F, 10G, 10H are embedded in the lowersurface of the peripheral plate 2 b. The shapes of the central plate 2 aand the peripheral plate 2 b are configured while taking intoconsideration the shape of the model for molding in the casting moldmolding device 29 and the positions of the green sand mold moldingsensors mentioned above. The shapes of the alignment sections of thecentral plate 2 a and the peripheral plate 2 b are configured so as toshare a common shape, and when a model for molding in the casting moldmolding device 29 is to be changed, the central plate 2 a which has themodels 3, 3 attached thereto only needs to be replaced.

FIG. 22(b) shows a state wherein the central plate 2 a is detached. Byloosening the bolts (not shown) and removing only the central plate 2 a,which has the models attached thereto, and attaching a central platehaving a different model attached thereto, it is possible to easilyexchange models without affecting the green sand mold molding sensors.

Thus, according to the green sand mold molding sensor of the secondembodiment, in order to determine the quality of a molded casting(casting mold strength), it is possible to measure, during molding of agreen sand mold, a pressure value (peak pressure) applied to a partingplane which is a joining section between the upper mold comprising greensand mold sand formed inside the cope 4 and the lower mold comprisinggreen sand mold sand formed inside the drag 5.

(Modifications)

In the first and second embodiments, after determining the relationshipbetween the casting mold strength and the pressure value (peak pressure)from the measured casting mold strength and the pressure value (peakpressure) measured by the green sand mold molding sensors 10A, 10B, 10C,10D (and 10E, 10F, 10G, 10H), the casting mold quality evaluation device12 separately calculates the casting mold strength from the pressurevalue (peak pressure) measured by the green sand mold molding sensors10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H). In addition, the quality ofa molded green sand mold is determined from the pre-set threshold valueof the casting mold strength and the calculated casting mold strength.

Additionally, by feeding back results determined by the casting moldquality evaluation device 12 to a kneading machine, it is possible toaccurately control the amount of water injected into the kneadingmachine. For example, if the pressure value (peak pressure) measured bythe green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F,10G, 10H) is extremely low and as a result thereof the casting moldstrength is extremely low, the casting mold quality evaluation device 12determines that the reason therefor is because sand was not filledevenly inside the casting mold and that the cause thereof is that the CBvalue of the green sand is high, and by providing an instruction to thekneading machine to reduce the amount of water injected, it is possibleto resolve the filling defect of the green sand.

Furthermore, by feeding back, to the kneading machine, resultsdetermined by the casting mold quality evaluation device 12 and resultsobtained by a green sand automatic measurement system, or the like,measuring and evaluating the compressive strength of the green sand, itis also possible to control the amount of additives, water, etc., loadedinto the kneading machine. For example, it is possible to perform anevaluation of the flowability, etc., of the green sand from: propertiesof the green sand measured by the green sand automatic measurementsystem such as the compressive strength, permeability, compactabilityvalue, water content value, etc. of the green sand; the pressure value(peak pressure) measured by the green sand mold molding sensors 10A,10B, 10C, 10D (and 10E, 10F, 10G, 10H); and the distribution thereof.Further, by changing the amount of additives, water content, etc.,loaded during kneading, it is possible to resolve casting mold defects.

Furthermore, in the first and second embodiments, the casting moldquality evaluation device 12 converts the pressure value (peak pressure)measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and10E, 10F, 10G, 10H) into a casting mold strength and determines thequality of molded green sand molds based on the converted casting moldstrength and the measured casting mold strength. However, since it hasbeen ascertained that there is a correlative relationship between thepressure value (peak pressure) and the casting mold strength, it is alsopossible to determine the quality of a green sand mold directly from thepressure value (peak pressure) without converting to the casting moldstrength. The first and second embodiments mentioned above are examplesin which two or more pressure sensors are provided to the plate.However, in the present invention, a configuration in which one pressuresensor is provided to the plate is also possible. In that case, it isdesirable that the position at which the pressure sensor is attached isnear the model of the plate. Further, in such cases when there is onepressure sensor, the output of the one pressure sensor also indicates avalue related to the casting mold strength at a specific position of thecasting mold. Therefore, accuracy decreases but it is possible to usethis value to perform an evaluation of the casting mold quality.

Various embodiments of the present invention are described above, butthe above descriptions do not limit the present invention and variousmodifications may be considered, including deletion, addition, andreplacement of constituent elements within the technical scope of thepresent invention.

REFERENCE SIGNS LIST

-   1 Casting mold molding device (frame casting mold molding)-   2 Plate-   2 a Central plate-   2 b Peripheral plate-   3 Model-   4 Carrier-   5 Metal frame-   6 Filling frame-   7 Squeeze head-   8 Squeeze board-   9 Table-   10A-10H Green sand mold molding sensor-   11 Wiring-   12 Casting mold quality evaluation device-   13 Liner-   14 Bolt-   15, 15′ Receiving unit-   16, 16′ Amplification unit-   17 Input unit-   18 Casting mold strength calculation unit-   19 Casting mold quality determination unit-   20 Display unit-   21 Transmission unit-   22 Recording unit-   23 Patlite-   24 Pressure value transmission unit-   25 Integrated amplifier-recorder-   26 Computer-   27 Louvered hopper-   28 Louver-   29 Casting mold molding machine (flaskless molding machine)-   30 Shuttle dolly-   31 Cope-   32 Drag-   33 Upper squeeze board-   34 Lower squeeze board-   35 Green sand blowing-in port-   36 Sand tank

1. A green sand mold molding sensor comprising a pressure sensor forevaluating moldability of a green sand mold molded by a casting moldmolding machine, wherein the pressure sensor is embedded in a platehaving a model attached thereto.
 2. The green sand mold molding sensoraccording to claim 1, wherein the plate having the model attachedthereto is a member that constitutes a part of a boundary of a moldingspace defined by the plate and a metal flask during green sand moldmolding by the casting mold molding machine.
 3. The green sand moldmolding sensor according to claim 1, wherein a pressure-receivingsurface of the pressure sensor and a surface of the plate are in a flushstate.
 4. The green sand mold molding sensor according to claim 1,wherein the pressure sensor is embedded between the wall of the metalflask and the model in the plate at the time of green sand mold molding.5. The green sand mold molding sensor according to claim 1, wherein theplate is configured to be rectangular, a plurality of the pressuresensors are provided, and these pressure sensors are embedded in thefour corners of the plate.
 6. The green sand mold molding sensoraccording to claim 1, wherein the plate having the model attachedthereto is divided into a central part having the model attached theretoand a peripheral part having the pressure sensor embedded therein, andthe central part of the plate having the model attached thereto isconfigured so as to be attachable and detachable.
 7. The green sand moldmolding sensor according to claim 1, wherein the casting mold moldingmachine is a flask molding machine and the plate is placed on a carrier.8. The green sand mold molding sensor according to claim 1, wherein thecasting mold molding machine is a flaskless molding machine and themodel is attached to both surfaces of the plate.
 9. The green sand moldmolding sensor according to claim 8, wherein the casting mold moldingmachine is a flaskless molding machine and the plate is placed on ashuttle dolly.
 10. The green sand mold molding sensor according to claim1, wherein the pressure sensor is fixed to the plate by a screwingmeans.
 11. The green sand mold molding sensor according to claim 1,wherein the pressure sensor is a fluid sensor.
 12. The green sand moldmolding sensor according to claim 1, wherein the pressure sensor has apressure-receiving surface that is 5-30 mm in diameter.
 13. A method forevaluating green sand mold moldability, wherein moldability of a greensand mold molded by a casting mold molding machine is evaluated by usinga green sand mold molding sensor comprising a pressure sensor embeddedin a plate having a model attached thereto.